SYNOPSIS

DESCRIPTION

gpg-agent is a daemon to manage secret (private) keys
independently from any protocol. It is used as a backend for
gpg and gpgsm as well as for a couple of other
utilities.

The usual way to run the agent is from the ~/.xsession file:

eval $(gpg-agent --daemon)

If you don't use an X server, you can also put this into your regular
startup file ~/.profile or .bash_profile. It is best not
to run multiple instance of the gpg-agent, so you should make
sure that only one is running: gpg-agent uses an environment
variable to inform clients about the communication parameters. You can
write the content of this environment variable to a file so that you can
test for a running agent. Here is an example using Bourne shell syntax:

This code should only be run once per user session to initially fire up
the agent. In the example the optional support for the included Secure
Shell agent is enabled and the information about the agent is written to
a file in the HOME directory. Note that by running gpg-agent without
arguments you may test whether an agent is already running; however such
a test may lead to a race condition, thus it is not suggested.

It reads the data out of the file and exports the variables. If you
don't use Secure Shell, you don't need the last two export statements.

You should always add the following lines to your .bashrc or
whatever initialization file is used for all shell invocations:

GPG_TTY=$(tty)
export GPG_TTY

It is important that this environment variable always reflects the
output of the tty command. For W32 systems this option is not
required.

Please make sure that a proper pinentry program has been installed
under the default filename (which is system dependant) or use the
option pinentry-program to specify the full name of that program.
It is often useful to install a symbolic link from the actual used
pinentry (e.g. oq/usr/bin/pinentry-gtkcq) to the expected
one (e.g. oq/usr/bin/pinentrycq).

COMMANDS

Commands are not distinguished from options except for the fact that
only one command is allowed.

--version

Print the program version and licensing information. Note that you cannot
abbreviate this command.

--help

-h

Print a usage message summarizing the most useful command-line options.
Note that you cannot abbreviate this command.

--dump-options

Print a list of all available options and commands. Note that you cannot
abbreviate this command.

--server

Run in server mode and wait for commands on the stdin. The
default mode is to create a socket and listen for commands there.

--daemon [command line]

Start the gpg-agent as a daemon; that is, detach it from the console
and run it in the background. Because gpg-agent prints out
important information required for further use, a common way of
invoking gpg-agent is: eval $(gpg-agent --daemon) to setup the
environment variables. The option --write-env-file is
another way commonly used to do this. Yet another way is creating
a new process as a child of gpg-agent: gpg-agent --daemon
/bin/sh. This way you get a new shell with the environment setup
properly; if you exit from this shell, gpg-agent terminates as well.

OPTIONS

--options file

Reads configuration from file instead of from the default
per-user configuration file. The default configuration file is named
oqgpg-agent.confcq and expected in the oq.gnupgcq directory directly
below the home directory of the user.

--homedir dir

Set the name of the home directory to dir. If this option is not
used, the home directory defaults to oq~/.gnupgcq. It is only
recognized when given on the command line. It also overrides any home
directory stated through the environment variable oqGNUPGHOMEcq or
(on W32 systems) by means of the Registry entry
HKCU\Software\GNU\GnuPG:HomeDir.

-v

--verbose

Outputs additional information while running.
You can increase the verbosity by giving several
verbose commands to gpgsm, such as aq-vvaq.

-q

--quiet

Try to be as quiet as possible.

--batch

Don't invoke a pinentry or do any other thing requiring human interaction.

--faked-system-time epoch

This option is only useful for testing; it sets the system time back or
forth to epoch which is the number of seconds elapsed since the year
1970.

--debug-level level

Select the debug level for investigating problems. level may be
a numeric value or a keyword:

none

No debugging at all. A value of less than 1 may be used instead of
the keyword.

basic

Some basic debug messages. A value between 1 and 2 may be used
instead of the keyword.

advanced

More verbose debug messages. A value between 3 and 5 may be used
instead of the keyword.

expert

Even more detailed messages. A value between 6 and 8 may be used
instead of the keyword.

guru

All of the debug messages you can get. A value greater than 8 may be
used instead of the keyword. The creation of hash tracing files is
only enabled if the keyword is used.

How these messages are mapped to the actual debugging flags is not
specified and may change with newer releases of this program. They are
however carefully selected to best aid in debugging.

--debug flags

This option is only useful for debugging and the behaviour may change at
any time without notice. FLAGS are bit encoded and may be given in
usual C-Syntax. The currently defined bits are:

0 (1)

X.509 or OpenPGP protocol related data

1 (2)

values of big number integers

2 (4)

low level crypto operations

5 (32)

memory allocation

6 (64)

caching

7 (128)

show memory statistics.

9 (512)

write hashed data to files named dbgmd-000*

10 (1024)

trace Assuan protocol

12 (4096)

bypass all certificate validation

--debug-all

Same as --debug=0xffffffff

--debug-wait n

When running in server mode, wait n seconds before entering the
actual processing loop and print the pid. This gives time to attach a
debugger.

--no-detach

Don't detach the process from the console. This is mainly useful for
debugging.

-s

--sh

-c

--csh

Format the info output in daemon mode for use with the standard Bourne
shell or the C-shell respectively. The default is to guess it based on
the environment variable SHELL which is correct in almost all
cases.

--write-env-file file

Often it is required to connect to the agent from a process not being an
inferior of gpg-agent and thus the environment variable with
the socket name is not available. To help setting up those variables in
other sessions, this option may be used to write the information into
file. If file is not specified the default name
oq${HOME}/.gpg-agent-infocq will be used. The format is suitable
to be evaluated by a Bourne shell like in this simple example:

eval $(cat file)
eval $(cut -d= -f 1 < file | xargs echo export)

--no-grab

Tell the pinentry not to grab the keyboard and mouse. This option
should in general not be used to avoid X-sniffing attacks.

--log-file file

Append all logging output to file. This is very helpful in seeing
what the agent actually does. If neither a log file nor a log file
descriptor has been set on a Windows platform, the Registry entry
HKCU\Software\GNU\GnuPG:DefaultLogFile, if set, is used to specify
the logging output.

--allow-mark-trusted

Allow clients to mark keys as trusted, i.e. put them into the
oqtrustlist.txtcq file. This is by default not allowed to make it
harder for users to inadvertently accept Root-CA keys.

--ignore-cache-for-signing

This option will let gpg-agent bypass the passphrase cache for all
signing operation. Note that there is also a per-session option to
control this behaviour but this command line option takes precedence.

--default-cache-ttl n

Set the time a cache entry is valid to n seconds. The default is
600 seconds.

--default-cache-ttl-ssh n

Set the time a cache entry used for SSH keys is valid to n
seconds. The default is 1800 seconds.

--max-cache-ttl n

Set the maximum time a cache entry is valid to n seconds. After
this time a cache entry will be expired even if it has been accessed
recently or has been set using gpg-preset-passphrase. The
default is 2 hours (7200 seconds).

--max-cache-ttl-ssh n

Set the maximum time a cache entry used for SSH keys is valid to
n seconds. After this time a cache entry will be expired even
if it has been accessed recently or has been set using
gpg-preset-passphrase. The default is 2 hours (7200
seconds).

--enforce-passphrase-constraints

Enforce the passphrase constraints by not allowing the user to bypass
them using the ``Take it anyway'' button.

--min-passphrase-len n

Set the minimal length of a passphrase. When entering a new passphrase
shorter than this value a warning will be displayed. Defaults to 8.

--min-passphrase-nonalpha n

Set the minimal number of digits or special characters required in a
passphrase. When entering a new passphrase with less than this number
of digits or special characters a warning will be displayed. Defaults
to 1.

--check-passphrase-pattern file

Check the passphrase against the pattern given in file. When
entering a new passphrase matching one of these pattern a warning will
be displayed. file should be an absolute filename. The default is
not to use any pattern file.

Security note: It is known that checking a passphrase against a list of
pattern or even against a complete dictionary is not very effective to
enforce good passphrases. Users will soon figure up ways to bypass such
a policy. A better policy is to educate users on good security
behavior and optionally to run a passphrase cracker regularly on all
users passphrases to catch the very simple ones.

--max-passphrase-days n

Ask the user to change the passphrase if n days have passed since
the last change. With --enforce-passphrase-constraints set the
user may not bypass this check.

--enable-passphrase-history

This option does nothing yet.

--pinentry-program filename

Use program filename as the PIN entry. The default is installation
dependent.

--pinentry-touch-file filename

By default the filename of the socket gpg-agent is listening for
requests is passed to Pinentry, so that it can touch that file before
exiting (it does this only in curses mode). This option changes the
file passed to Pinentry to filename. The special name
/dev/null may be used to completely disable this feature. Note
that Pinentry will not create that file, it will only change the
modification and access time.

--scdaemon-program filename

Use program filename as the Smartcard daemon. The default is
installation dependent and can be shown with the gpgconf
command.

--disable-scdaemon

Do not make use of the scdaemon tool. This option has the effect of
disabling the ability to do smartcard operations. Note, that enabling
this option at runtime does not kill an already forked scdaemon.

--use-standard-socket

--no-use-standard-socket

By enabling this option gpg-agent will listen on the socket
named oqS.gpg-agentcq, located in the home directory, and not create
a random socket below a temporary directory. Tools connecting to
gpg-agent should first try to connect to the socket given in
environment variable GPG_AGENT_INFO and then fall back to this
socket. This option may not be used if the home directory is mounted on
a remote file system which does not support special files like fifos or
sockets.
Note, that --use-standard-socket is the default on
Windows systems.
The default may be changed at build time. It is
possible to test at runtime whether the agent has been configured for
use with the standard socket by issuing the command gpg-agent
--use-standard-socket-p which returns success if the standard socket
option has been enabled.

--display string

--ttyname string

--ttytype string

--lc-ctype string

--lc-messages string

--xauthority string

These options are used with the server mode to pass localization
information.

--keep-tty

--keep-display

Ignore requests to change the current tty or X window system's
DISPLAY variable respectively. This is useful to lock the
pinentry to pop up at the tty or display you started the agent.

--enable-ssh-support

Enable the OpenSSH Agent protocol.

In this mode of operation, the agent does not only implement the
gpg-agent protocol, but also the agent protocol used by OpenSSH
(through a separate socket). Consequently, it should be possible to use
the gpg-agent as a drop-in replacement for the well known ssh-agent.

SSH Keys, which are to be used through the agent, need to be added to
the gpg-agent initially through the ssh-add utility. When a key is
added, ssh-add will ask for the password of the provided key file and
send the unprotected key material to the agent; this causes the
gpg-agent to ask for a passphrase, which is to be used for encrypting
the newly received key and storing it in a gpg-agent specific
directory.

Once a key has been added to the gpg-agent this way, the gpg-agent
will be ready to use the key.

Note: in case the gpg-agent receives a signature request, the user might
need to be prompted for a passphrase, which is necessary for decrypting
the stored key. Since the ssh-agent protocol does not contain a
mechanism for telling the agent on which display/terminal it is running,
gpg-agent's ssh-support will use the TTY or X display where gpg-agent
has been started. To switch this display to the current one, the
following command may be used:

gpg-connect-agent updatestartuptty /bye

Although all GnuPG components try to start the gpg-agent as needed, this
is not possible for the ssh support because ssh does not know about it.
Thus if no GnuPG tool which accesses the agent has been run, there is no
guarantee that ssh is abale to use gpg-agent for authentication. To fix
this you may start gpg-agent if needed using this simple command:

gpg-connect-agent /bye

Adding the --verbose shows the progress of starting the agent.

All the long options may also be given in the configuration file after
stripping off the two leading dashes.

EXAMPLES

The usual way to invoke gpg-agent is

$ eval $(gpg-agent --daemon)

An alternative way is by replacing ssh-agent with
gpg-agent. If for example ssh-agent is started as
part of the Xsession initialization, you may simply replace
ssh-agent by a script like:

FILES

There are a few configuration files needed for the operation of the
agent. By default they may all be found in the current home directory
(see: [option --homedir]).

gpg-agent.conf

This is the standard configuration file read by gpg-agent on
startup. It may contain any valid long option; the leading
two dashes may not be entered and the option may not be abbreviated.
This file is also read after a SIGHUP however only a few
options will actually have an effect. This default name may be
changed on the command line (see: [option --options]).
You should backup this file.

trustlist.txt

This is the list of trusted keys. You should backup this file.

Comment lines, indicated by a leading hash mark, as well as empty
lines are ignored. To mark a key as trusted you need to enter its
fingerprint followed by a space and a capital letter S. Colons
may optionally be used to separate the bytes of a fingerprint; this
allows to cut and paste the fingerprint from a key listing output. If
the line is prefixed with a ! the key is explicitly marked as
not trusted.

Here is an example where two keys are marked as ultimately trusted
and one as not trusted:

.RS 2

# CN=Wurzel ZS 3,O=Intevation GmbH,C=DE
A6935DD34EF3087973C706FC311AA2CCF733765B S
# CN=PCA-1-Verwaltung-02/O=PKI-1-Verwaltung/C=DE
DC:BD:69:25:48:BD:BB:7E:31:6E:BB:80:D3:00:80:35:D4:F8:A6:CD S
# CN=Root-CA/O=Schlapphuete/L=Pullach/C=DE
!14:56:98:D3:FE:9C:CA:5A:31:6E:BC:81:D3:11:4E:00:90:A3:44:C2 S
.fi
Before entering a key into this file, you need to ensure its
authenticity. How to do this depends on your organisation; your
administrator might have already entered those keys which are deemed
trustworthy enough into this file. Places where to look for the
fingerprint of a root certificate are letters received from the CA or
the website of the CA (after making 100% sure that this is indeed the
website of that CA). You may want to consider allowing interactive
updates of this file by using the see: [option --allow-mark-trusted].
This is however not as secure as maintaining this file manually. It is
even advisable to change the permissions to read-only so that this file
can't be changed inadvertently.
As a special feature a line include-default will include a global
list of trusted certificates (e.g. oq/etc/gnupg/trustlist.txtcq).
This global list is also used if the local list is not available.
It is possible to add further flags after the S for use by the
caller:

relax

Relax checking of some root certificate requirements. As of now this
flag allows the use of root certificates with a missing basicConstraints
attribute (despite that it is a MUST for CA certificates) and disables
CRL checking for the root certificate.

cm

If validation of a certificate finally issued by a CA with this flag set
fails, try again using the chain validation model.

sshcontrol

This file is used when support for the secure shell agent protocol has
been enabled (see: [option --enable-ssh-support]). Only keys present in
this file are used in the SSH protocol. You should backup this file.
The ssh-add tool may be used to add new entries to this file;
you may also add them manually. Comment lines, indicated by a leading
hash mark, as well as empty lines are ignored. An entry starts with
optional whitespace, followed by the keygrip of the key given as 40 hex
digits, optionally followed by the caching TTL in seconds and another
optional field for arbitrary flags. A non-zero TTL overrides the global
default as set by --default-cache-ttl-ssh.
The only flag support is confirm. If this flag is found for a
key, each use of the key will pop up a pinentry to confirm the use of
that key. The flag is automatically set if a new key was loaded into
gpg-agent using the option -c of the ssh-add
command.
The keygrip may be prefixed with a ! to disable an entry entry.
The following example lists exactly one key. Note that keys available
through a OpenPGP smartcard in the active smartcard reader are
implicitly added to this list; i.e. there is no need to list them.
.RS 2
# Key added on: 2011-07-20 20:38:46
# Fingerprint: 5e:8d:c4:ad:e7:af:6e:27:8a:d6:13:e4:79:ad:0b:81
34B62F25E277CF13D3C6BCEBFD3F85D08F0A864B 0 confirm
.fi

private-keys-v1.d/

This is the directory where gpg-agent stores the private keys. Each
key is stored in a file with the name made up of the keygrip and the
suffix oqkeycq. You should backup all files in this directory
and take great care to keep this backup closed away.
Note that on larger installations, it is useful to put predefined
files into the directory oq/etc/skel/.gnupg/cq so that newly created
users start up with a working configuration. For existing users the
a small helper script is provided to create these files (see: [addgnupghome]).

SIGNALS

A running gpg-agent may be controlled by signals, i.e. using
the kill command to send a signal to the process.

Here is a list of supported signals:

SIGHUP

This signal flushes all cached passphrases and if the program has been
started with a configuration file, the configuration file is read
again. Only certain options are honored: quiet,
verbose, debug, debug-all, debug-level,
no-grab, pinentry-program, default-cache-ttl,
max-cache-ttl, ignore-cache-for-signing,
allow-mark-trusted, disable-scdaemon, and
disable-check-own-socket. scdaemon-program is also
supported but due to the current implementation, which calls the
scdaemon only once, it is not of much use unless you manually kill the
scdaemon.

SIGTERM

Shuts down the process but waits until all current requests are
fulfilled. If the process has received 3 of these signals and requests
are still pending, a shutdown is forced.